Fri, February 17, 2006 4:07 PM
Checkpoint: Motor Stall Test
Today we had our motor stall test checkpoint. For this test, we were required to build a single-MOSFET motor driver, and be able to drive a brushed DC car motor at 50% duty cycle, from the battery, with the wheels clamped, for 10-15 seconds. We passed with flying colors, even at a 20 kHz PWM frequency (they're recommending to everyone else to run at 100-200 Hz), so he offered us extra credit: a "check-plus" if we can pass the same test at 90% duty cycle.
We tried it. The MOSFET had no problem, but the motor started to smoke! We stopped as soon as we saw that. We got the check-plus, too.